It is widely recognized that the function of a detergent additive material can be significantly impaired in a detergent composition by interaction between the additive material and other components of the composition. For example, enzymes, perfumes and bleach activators can be deleteriously effected by interaction with peroxy bleaches; cationic fabric conditioners can be deleteriously effected by interaction with anionic surfactants; and fluorescers can be deleteriously effected by interaction with peroxy bleaches or cationic surfactants. Moreover, the consumer acceptability of a product can also be significantly reduced as the result of physical interactions between a detergent additive and other components of a detergent composition. For instance, a speckled detergent containing a water-soluble dye can lose its aesthetic appeal as a result of migration of the dye into the detergent base powder, an effect which can be significantly enhanced by the presence in the detergent composition of a nonionic surfactant component. Physical segregation problems in the case of abnormally-sized additive materials can also contribute to reduced aesthetic appeal and effectiveness of a detergent composition.
The Applicants have now discovered that detergent additive materials having improved storage stability in a detergent composition, can be provided by releasably enclosing the additive material within a glassy matrix of amorphous phosphate material. The idea of coating, agglomerating or encapsulating sensitive ingredients to provide improved storage stability is well known, of course. Conventionally, organic materials have found the greatest favour as coating agents because such materials readily form the substantially continuous barrier necessary for effective stabilization of the additive material. British Pat. Nos. 1,204,123, 1,441,416 and 1,395,006 are representative of this general approach. However, organic coating materials suffer the disadvantage that, to be efficaceous, the coating material must be so water impervious (i.e., hydrophobic) and also possibly so high melting as to inhibit considerably the rate of release of the additive material into a detergent wash liquor. By contrast, the coating materials of the present invention provide a matrix which effectively encloses and protects the detergent additive material, yet which is readily water-soluble and provides for rapid release of the additive material into a bulk detergent liquor.